The present disclosure relates to a photogrammetry system that includes a movable photographing device taking images for photogrammetry and a surveying device determining a position of the movable photographing device.
In typically known stereophotogrammetry, a movable body includes a camera, which takes images (static images and dynamic images) from two or more different positions, the images being used for a survey.
In particular, in recent photogrammetry, an unmanned aerial vehicle (UAV) is used as a movable body including a camera, which takes images from the sky.
In such photogrammetry, a spatial position of each image taken is adjusted to generate a stereo model of target areas.
For example, in Japanese Unexamined Patent Publication No. 2013-108927, a flying body flies in the sky above target survey areas in a meandering manner to take images. This photographing operation is periodically conducted so that each image overlaps an image adjacent thereto in the travelling direction by a predetermined amount, and overlaps an image adjacent thereto in an adjacent course by a predetermined amount. After all the photographing operations are completed, one pair of two adjacent ones of three images consecutive in the travelling direction is fixed so that one stereo image is produced. The other pair of two adjacent ones of the three images is also fixed so that the other image is produced. Feature points extracted from a portion shared by the three images in the image shared by the two stereo images are used to connect the two stereo images. Moreover, a tie point shared by the images adjacent to each other in the adjacent course is selected to connect the stereo images adjacent to each other in the course. Consequently, all the target survey areas are covered. In this manner, a unified stereo image (a stereo model) represented by the shared three-dimensional coordinate system is produced.